Question

When a sample of compound is considered to be optically pure:

• A. if only one enantiomer is present
• B. no enantiomer is present
• C. if the compound is having racemic mixture
• D. none

Answer 1

Answer: (A)

if only one enantiomer is present

If only one enantiomer is present a compound of a sample is considered to be optically pure because it shows some net rotation as it is not having another isomer of it, it does not show any opposite rotation.

When a sample consists of a mixture of enantiomers, the effect of each enantiomer cancels out.

Hence, the correct option is $\text{A}$.